21220302221 has 4 divisors (see below), whose sum is σ = 21220781052. Its totient is φ = 21219823392.

The previous prime is 21220302217. The next prime is 21220302223. The reversal of 21220302221 is 12220302212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13482460996 + 7737841225 = 116114^2 + 87965^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220302221 - 2² = 21220302217 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21220302221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220302223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 165290 + ... + 264123.

It is an arithmetic number, because the mean of its divisors is an integer number (5305195263).

Almost surely, 2^21220302221 is an apocalyptic number.

It is an amenable number.

21220302221 is a deficient number, since it is larger than the sum of its proper divisors (478831).

21220302221 is an equidigital number, since it uses as much as digits as its factorization.

21220302221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478830.

The product of its (nonzero) digits is 192, while the sum is 17.

Adding to 21220302221 its reverse (12220302212), we get a palindrome (33440604433).

Subtracting from 21220302221 its reverse (12220302212), we obtain a palindrome (9000000009).

The spelling of 21220302221 in words is "twenty-one billion, two hundred twenty million, three hundred two thousand, two hundred twenty-one".